by Paul Myerberg, USA TODAY Sports

by Paul Myerberg, USA TODAY Sports

Think back to Week 7 of 2012. Who led the charge for the Heisman Trophy? Probably Kansas State quarterback Collin Klein, who led the Wildcats to 55-24 takedown of West Virginia and ex-Heisman frontrunner Geno Smith; behind Klein was Ohio State quarterback Braxton Miller, Alabama quarterback AJ McCarron and Notre Dame linebacker Manti Te'o, in some order or another.

Who wasn't listed among the top five Heisman contenders at last year's midway point? Try Texas A&M quarterback Johnny Manziel, then a redshirt freshman starter on a 5-2 team fresh off a 24-19 loss to LSU. The lesson: Heisman watch lists are useful, but history suggests your leaders today might not be your leaders tomorrow.

With seven weeks of the 2013 season in the books, here are 10 top contenders for the Heisman:

Mariota responded flawlessly in Oregon's first true test of 2013, a trip to rowdy and raucous Husky Stadium, and cemented his grasp atop the Heisman hill as the season breaks through the midway point. Better yet, Mariota has several additional opportunities to impress the masses down the stretch â?? UCLA, Stanford and Oregon State, for starters.

The smile said it all: Detractors saw cockiness on Manziel's face as he flashed a grin late in the fourth quarter â?? and were right, since the sophomore saw that Mississippi had left the Aggies' offense more than enough time to pull out a game-winning drive. When the lights are bright and the chips are downs, there is no better player in college football.

Boyd meets Jameis Winston in Saturday's season-deciding ACC tilt in Death Valley â?? well, Clemson hosts Florida State, but you get the idea. Beyond settling the Atlantic Division and the ACC title, one would think, Saturday's game should provide an enormous boost to one of the pair's Heisman credentials.

Is Winston ready to take on a solid defense in a hostile environment? While he's played far beyond his years through five games, Death Valley will provide a wholly different set of circumstances for the redshirt freshman to handle. The good news: Winston has already taken on the entire kitchen sink, pretty much, and passed every test with flying colors.

5. Alabama QB AJ McCarron (Last week's ranking: No. 7)

Season stats: 111-of-161 for 1,407 yards; 11 touchdowns, three interceptions

McCarron has been superb the last two weeks, albeit against terrible competition â?? first Georgia State, then Kentucky. But he's done what all expected, which is play error-free football and pilot the nation's best team to a perfect start; he's also provided fireworks when needed, as in the win at Texas A&M.

Petty's best game came in the Baylor's worst performance of the 2013 season, if that makes sense. Facing a stiff test against Kansas State â?? the Bears' first road game of the year â?? Petty responded with four touchdowns, three through the air, and led his offense to a pair of fourth-quarter scoring drives to pull out a 10-point win. One fact to remember: Petty is averaging 14.8 yards per attempt. In comparison, last season's leading passer, Marshall's Rakeem Cato, averaged 10.4 yards per completion.

7. Louisville QB Teddy Bridgewater (Last week's ranking: No. 6)

Season stats: 125-of-176 for 1,872; 18 touchdowns, two interceptions

Bridgewater's numbers remained terrific â?? 310 yards, a pair of scores, 21 completions in 31 attempts â?? but he was somewhat rattled by Rutgers' pass rush, as was Louisville's entire offense. While certainly very much still in the Heisman conversation, Bridgewater likely could have used a stronger showing during a nationally televised Thursday night game.

Georgia's second loss sends Murray tumbling, though he's only down, not out. There are opportunities down the stretch: Florida is one, perhaps Auburn another, and there's always the opportunity to take out a team like Alabama in the SEC title game. But with skill players dropping left and right, Murray has an uphill push for the Heisman.

9. Ohio State QB Braxton Miller (Last week's ranking: No. 8)

Season stats: 49-of-75 for 609 yards; six touchdowns, two interceptions; 57 carries for 233 yards

Ohio State's bye week seems to come at a good time for Miller, who likely needed some extra time to fully recover from September's knee injury. His greatest Heisman asset is one that simply cannot be ignored: Miller is the starting quarterback for one of the best teams in the country, and one that seems very much destined for a perfect, unblemished run to the postseason.

10. Fresno State QB Derek Carr (Last week's ranking: No. 9)

Season stats: 183-of-259 for 1,864 yards; 19 touchdowns, four interceptions

Carr has earned the requisite non-AQ spot based on his own production, not to mention the way Northern Illinois quarterback Jordan Lynch struggled throwing the football in Saturday's win against Akron. If a long shot for the trophy, Carr can earn an invite to Manhattan with a strong second half â?? and if he leads the Bulldogs to 12-0 and the doorstep of an at-large BCS bid.